EP1670836A1

EP1670836A1 - Catalyst system for producing diene and vinyl aromatic homopolymers and copolymers by anionic polymerisation

Info

Publication number: EP1670836A1
Application number: EP04765819A
Authority: EP
Inventors: Walter Hellermann
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-10-09
Filing date: 2004-10-05
Publication date: 2006-06-21
Also published as: DE102004048750A1; WO2005035599A1

Abstract

The invention relates to a method for producing, if necessary, coupled non-aligned polymers based on conjugated dienes or copolymers based on conjugated dienes and vinyl aromatic compounds by anionic polymerisation in an inert organic solvent in the presence of a catalyst system which consists of (a) at least one lithium organic compound in the form of an initiator, (b) at least one polar multidentate acetal compound in the form of a modifier and (c) at least one type of alcoholate, if necessary. The inventive method makes it possible to advantageously produce diene and vinyl aromatic homopolymers and copolymers provided with a specific structure, in particular at high polymerisation temperatures, thereby reducing reaction duration.

Description

Catalyst system for the production of homopolymers and copolymers of dienes and vinylaromatics by anionic polymerization

The present invention relates to a process for the production of optionally coupled non-blocking polymers based on conjugated dienes and optionally monovinylaromatic compounds by anionic polymerization, and to the process products or polymers prepared in this way and their use, in particular for the production of damping materials, tires and tire components as well as technical rubber articles.

The development of tires with a perfected property profile represents a complex optimization task in which the tire manufacturer moves in the area of tension between the magic triangle of rolling resistance, abrasion resistance and wet skid resistance. In order to improve the wet slip behavior, it is necessary to manufacture tire rubbers with the highest possible glass temperature, as is the case, for. B. with the 3,4-polyisoprene rubber as a molecular building block with the highest glass transition temperature of all molecular segments that can be produced by anionic polymerization. In the case of the modern solution SBR rubbers, this leads to tire polymers with the highest possible 1,2-vinyl and 3, 4-structural units. At the same time, the trend in anionically produced butadiene styrene rubbers is towards higher styrene contents of more than 25%, based on the entire polymer. The requirements for the randomizer effect of the microstructure controllers used then increase significantly.

Basic polar compounds, so-called modifiers, randomizers or microstructure regulators, are used in modern solution polymers both for the homopolymerization and for the copolymerization of dienes and vinylaromatics in order to adjust these tailored microstructures. The terms "modifier", "microstructure controller" and "randomizer" are thus used synonymously in the context of the present invention.

The disadvantage of the prior art modifiers is that their efficiency drops significantly at high polymerization temperatures. Furthermore, in most cases they have only a weak influence on the statistical incorporation of the vinylaromatic component, ie there is a poor randomizer effect.

Numerous compounds are known from the prior art which have an influence on the course of the polymerization with regard to the preferred formation of 1,2- and 3,4-structural units (cf. e.g. BKH Nordsiek, KM Kiepert, Kautschuk und Gummi, Kunststoffe 35, 371 (1982) and KH Nordsiek, caoutchouc and rubber, Kunststoffe 39, 599 (1986)).

Numerous ethers, amines, phosphines, etc. have been proposed as microstructure regulators in the past (DE 27 07 761 C2 and DE 31 15 878 C2). However, since these substances alone do not have a satisfactory randomizing effect, surface-active agents must also be used for the statistical incorporation of the monomers in the polymer molecule.

EP-A-0 304 589 describes certain ethylene glycol dialkyl ethers as suitable microstructure regulators. However, these compounds show a significant drop in the microstructural control action at higher polymerization temperatures and at the same time do not have an optimal randomizer action. A major disadvantage of the microstructure regulators of the prior art is the frequently weakening regulating action when the polymerization temperature rises. It is known, for example, that with the frequently used microstructure regulator tetramethylethylenediamine (TMEDA) in isoprene polymerization, with a microstructure regulator / initiator molar ratio of about 5, high levels of 3,4-structural units occur, but at the same time the polymerization rate drops significantly (cf. WL Hau , AF Halasa and TT Wetli, Rubber Chemistry and Technology 71, pages 62 ff. (1998)). EP 0 507 222 AI and US-A-5 112 929 claim for this purpose cyclic 1,3-dioxolane acetals, such as. B. 2- (2-oxolanyl) dioxolane, as a microstructure regulator for the anionic polymerization of dienes. However, no statement is made regarding the polymerization rates achieved with this. In US-A-5 552 490, US-A-5 231 153, US-A-5 470 929, US-A-5 488 003 and US-A-5 359 016, alkyl tetrahydrofurfuryl ethers are essentially suitable Modifier for the anionic Polymerization of dienes described. These regulators are said to be able to achieve much higher polymerization rates in the case of isoprene polymerization than in the case of TMEDA. However, these connections are still too slow and at the same time are noticeable in the rubber by an unpleasant smell.

In DE 102 43 618 AI and WO 03/044065 A2 microstructure regulators based on bidentate and tridentate Lewis bases of alkylamino ethers or cyclic dioxolane (dioxane) alkyl ethers and cyclic oxolane (dioxane) alkylamino ethers are mentioned, which for Production of homopolymers and copolymers of dienes and vinylaromatics can be used at high polymerization temperatures.

US Pat. No. 5,300,599 describes alcoholates based on tetrahydrofurfuryl alcohol, which can be used as modifiers in anionic solution polymerization. To further increase the rate of polymerization, alcoholates are added in many cases in addition to the polar modifier. For example, US Pat. Nos. 5,906,956 and 5,667,402 describe a complex anionic initiator system which simultaneously consists of a lithium initiator, a sodium alcoholate and a polar modifier. Likewise, the US patent application 2002/0045720 AI describes a complex initiator system consisting of a lithium initiator, a calcium alcoholate and a lithium alkoxide, but only styrene / butadiene copolymers with a low 1,2 content can be produced.

The improvement of the randomizer effect of unsymmetrical dialkyl ethers by adding alkali metal alcoholates, such as. B. sodium tert-amylate is mentioned in DE 102 34 746 AI.

Starting from the prior art listed above, there is no process for the preparation of polymers in which at least two compounds from the group of butadiene, isoprene and styrene are used and in which the requirements, such as • good control effect even at high polymerization temperatures and low concentration of the regulator; • Improve the rate of polymerization and complete conversion; • good stability, ie no break off of the living chain ends; • Good randomizer effect and thus statistical incorporation of the vinyl aromatics, all of which are ideally fulfilled at the same time. Depending on the specific conditions of the respective polymerization plant, the focus in the requirements can also be weighted differently.

It is therefore an object of the present invention to develop such a method.

Another object of the present invention is to provide a method of the type described above which at least largely avoids or at least mitigates the aforementioned disadvantages of the prior art.

Yet another object of the invention is to produce non-blocking polymers (ie, in the case of diene copolymerization, the styrene units should be largely incorporated statically in the polymer chain, so that the copolymers can be used, in particular, for producing tires and damping materials and technical rubber articles, for example) , In particular, the polymers or rubbers obtainable by this process should have a glass transition temperature in the range from -70 ° C. to +10 ° C., in particular -30 ° C. to 0 ° C.

The subject of the present invention - according to a first aspect of the present invention - is thus a method according to claim 1. Further advantageous embodiments are the subject of the subordinate claims (claims 2 to 20). Another object of the present invention - in accordance with a second aspect of the present invention - are the products or polymers (ie rubbers) obtainable by the process according to the invention. The process products or polymers (ie polymers or copolymers) according to the invention are particularly noteworthy by a high proportion of 1,2-structural units of butadiene and 1,2- and 3,4-structural units of isoprene.

Yet another object of the present invention - according to a third aspect of the present invention - is the use of the products or polymers obtainable by the process according to the invention, as described in more detail in claims 22 to 26.

Yet another object of the present invention - according to a fourth aspect of the present invention - are the products produced with the polymers obtainable according to the invention, in particular damping materials, tires and tire components (e.g. tire treads or sidewalls) and technical rubber articles, according to claim 27. Finally, a further object of the present invention - according to a fifth aspect of the present invention - is the use of a catalyst system used according to the invention as described in claim 26, as described in claims 1 to 20. The present invention therefore relates, inter alia, to a process for the production of optionally coupled non-blocking polymers based on conjugated dienes and, if appropriate, monovinylaromatic compounds, in particular at high temperatures, and the process products obtainable in this way and their use for the production of tires and tire parts, damping elements and technical rubber materials. The process products are characterized by a high proportion of 1,2-structural units of butadiene and 1,2- and 3,4-structural units of isoprene. The subject of the present invention - according to a first aspect of the present invention - is thus a method for producing given if appropriate, coupled non-blocking polymers based on conjugated dienes or copolymers based on conjugated dienes and vinylaromatic compounds by anionic polymerization in an inert organic solvent in the presence of a catalyst system, the catalyst system (a) comprising at least one organolithium compound (e.g. an alkyl lithium umverbindung) as initiator, (b) at least one polar multidentate acetal compound (= ether compound) as modifier and (c) optionally at least one alcoholate.

Furthermore, it has now been found, unexpectedly, that the good microstructure control action of the polar, in particular multidentate acetal or ether compounds and the acceleration of the reaction of the simple alcoholates according to the prior art can be significantly improved by the alcoholates used according to the invention.

In an embodiment preferred according to the invention, alcoholates of the following general formula M ¹ - OR or RO - M - OR "are used as alcoholates in the process according to the invention, where • M ¹ denotes an alkali metal, preferably lithium, potassium or sodium; M denotes an alkaline earth metal, preferably calcium or magnesium; and R 'and R ", each independently of one another, denotes an alkyl, aryl, arylalkyl radical or a hydrocarbon radical which contains oxygen and / or nitrogen contains substance, designate (The alkyl group preferably consists of 2 to 8 carbon atoms, with the sodium alcoholates being preferred.).

The alcoholates optionally used according to the invention are in a non-polar hydrocarbon by reaction z. B. with sodium or potassium and the corresponding alcohols by standard methods. In the case of e.g. B. Calcium and magnesium are assumed from Ca (OH) ₂ or Mg (OH) ₂ .

At the same time, the present invention shows that the alkyl acetals according to the general formula (I)

can be used as modifiers in anionic diene polymerization, where:

A denotes a radical -OR ¹ or a radical -NR ⁴ R ⁵ , where R ¹ , R and R ⁵ , each independently of the other, denote a C _r C ₄ alkyl radical; B denotes a CC ₄ -alkyl radical or a radical -OR ⁶ with R ⁶ = C, -C ₄ -alkyl or is hydrogen; • R ⁷ denotes a C _r C ₄ alkyl radical or is hydrogen; R "and R each independently of one another represent C _r C ₄ alkyl radicals or R ² and R ³ are bonded to one another and together form an alkylene group, in particular an ethylene, propylene or butylene group, to form a five-, to form a six- or seven-membered ring (ie a 1,3-dioxolane, 1,3-dioxane or 1,3-dioxepane ring); • m is 0 or 1; and • n is 0, 1 or 2; however with the proviso that, when n = 0 and m = 0, A denotes a residue -OR ¹ , as previously defined, and B denotes a residue -OR ⁶ , as previously defined. These alkyl acetals have both the properties of a good microstructure regulator and those of a good randomizer. Compared to the many other known Lewis bases, the alkyl acetals used according to the invention also show a pronounced microstructure control action even at high polymerization temperature (ie short reaction times). These alkyl acetals can be used both alone with the initiator and at the same time in combination with the alcoholates provided according to the invention.

Another advantage of the aforementioned alkyl acetals is their relatively good accessibility, either as commercially available products or through manageable synthesis methods. Another advantage of these alkyl acetals is that many of these compounds are EINECS-listed - EINECS is the abbreviation for European Inventory of Existing Commercial Substances - so that costly approval procedures are not necessary.

According to a particular embodiment of the present invention, the following alkyl acetals according to the general formula (I a) are used as modifiers of the aforementioned type

used, wherein • A denotes a radical -OR ¹ or a radical -NR ⁴ R ⁵ , where R ¹ , R ⁴ and R ⁵ , each independently of the other, denote a C _r C ₄ alkyl radical; • B denotes a CC ₄ -alkyl radical or a radical -OR ⁶ with R ⁶ = C, -C ₄ -alkyl or is hydrogen; • R ² and R ³ each independently represent C, -C ₄ alkyl radicals; and • n is 0, 1 or 2. According to a particular embodiment of this particular embodiment, the radicals R ¹ to R ⁵ , each independently of one another, represent a methyl or ethyl radical, preferably an ethyl radical, the radical B can denote hydrogen and n can be 0 or 1.

According to another particular embodiment of this particular embodiment, the alkyl radicals R ¹ to R ⁵ , each independently of one another, represent a methyl or ethyl radical, the radical A can be a group —OR ¹ , as previously defined, the radical B can denote hydrogen and n can be 0 or 1.

According to this embodiment, particular preference is given to using alkyl acetals which are selected from the group consisting of 1, 1, 2-triethoxyethane, l, l-diethoxy-2-methoxyethane, l-ethoxy-l, 2-dimethoxyethane, 1, 1,2-trimethoxyethane, 2-ethoxy-l, l-dimethoxyethane, 1,2-diethoxy-l-methoxyethane and (2-methoxyethoxy) acetaldehyde dimethyl acetal.

According to this embodiment, particular preference is likewise given to using alkyl acetals which are selected from the group consisting of 1,1,2,2-tetraethoxyethane, 1, 1,2,2-tetramefhoxyethane, 1, 1,3,3-tetraethoxypropane and 1,1,3,3-tetramethoxypropane.

According to a further special, alternative embodiment of the present invention, the following alkyl acetals according to the general formula (Ib) are used as modifiers of the aforementioned type

used, wherein the radical R independently of one another denotes a C _r C ₄ alkyl radical n Q or hydrogen, x is equal to 0.1 or 2 and the radicals R, R and R ¹⁰ , each independently of one another, represent C _r C ₄ alkyl radicals , According to a special embodiment of this embodiment, the radical R can be a methyl or ethyl radical, preferably a methyl radical R and R radicals, each independently of the other, represent methyl or ethyl radicals, the radical R can be hydrogen and x can be 0. According to this embodiment, 2,2-dimethoxymethyl-1,3-dioxolane or 2,2-diethoxymethyl-1,3-dioxolane are very particularly preferably used as modifiers.

It may be advantageous, in addition to the modifiers or alkyl acetals used according to the invention, such as. B. the substituted 1,3-dioxolane derivatives, according to the general formulas given above, add a potassium or sodium alcoholate in order to further improve the statistical distribution of the styrene units in the copolymers. For this purpose, the alkali metal or alkaline earth metal salts, in particular potassium or sodium salts, mono- or polyhydric alcohols and phenols and mono- or polyvalent carboxylic acids come into consideration. The alkyl groups with 2 to 8 carbon atoms are particularly suitable. In general, the potassium compounds are preferred. Examples include the sodium or potassium salts of dimethylamine, di-n-butylamine, dibutylamine, lauric acid, palmitic acid, stearic acid, benzoic acid, phthalic acid, methyl alcohol, ethyl alcohol, isopropyl alcohol, propyl alcohol, tert-butyl alcohol, tert. -Amyl alcohol, n-hexyl alcohol, cyclohexyl alcohol or phenol. Potassium tert-butoxide and potassium tert-amylate are particularly preferably used. The molar ratio of microstructure regulator to alcoholate can be in the range from 1: 0.1 to 1: 1. Anionic surface-active compounds with a hydrophilic group, such as. B. -S0 ₃ M or -OS0 ₃ M, where M is potassium or sodium or rubidium, are additionally added to the initiator. Examples are salts of alkylarylsulfonic acids, such as. As potassium stearyl benzene sulfonate, potassium dodecyl benzene sulfonate, potassium nonyl benzene sulfonate and potassium decyl benzene sulfonate or salts of sulfuric acid esters of higher alcohols, such as. As potassium stearyl sulfate, potassium dodecyl sulfate, potassium decyl sulfate, potassium nonyl sulfate and potassium N-methyl taurate, to name a few.

An inert organic solvent is used as the reaction medium. Particularly suitable are hydrocarbons with 5 to 12 carbon atoms, such as Pentane, hexane, heptane and octane, and their cyclic analogues. Aromatic solvents, such as. As benzene, toluene and the like. Mixtures of the compounds described above can of course also be used.

In particular, alkyl lithium compounds are used as catalyst (= initiator or starter), which are easily accessible by reacting lithium with the corresponding alkyl halides. The alkyl radicals have 1 to 10 carbon atoms. Individual hydrogen atoms can be substituted by phenyl radicals. The following alkyl lithium compounds are particularly suitable: methyl lithium, ethyl lithium, pentyllithium. Sec. And n-butyl lithium are preferred. In principle, bifunctional organic lithium compounds can also be used. However, these are less accessible and, in particular, less inexpensive than their monofunctional analogues if one wishes to produce star-shaped solution rubbers. The amount of catalyst used depends on the molecular weight to be adjusted. This is usually in the range of 50,000 to 1,500,000. The modifier and the alcoholate are preferably metered in at the start of the reaction. However, the modifier or the alcoholate can also be added during the polymerization, if this should be expedient for certain reasons. Likewise, the modifiers according to the invention can be used individually or in any proportion to one another.

Based on one mole of the lithium alkyl initiator, amounts of 0.1 to 15 mol of modifier (s) are used in anionic polymerization with the modifiers used according to the invention, and amounts of 0.1 to 10 mol are used for the alcoholates. In principle, the catalyst system used according to the invention can be metered in different variants. On the one hand, the modifier and the alcoholate can be added individually before the actual polymerization, the alcoholate expediently in an inert solvent, such as. B. heptane is dissolved. Another preferred embodiment consists in using the alcoholate in admixture with the modifications according to the invention. The solubility is sufficient and the necessary amount In this way, alcoholate can be introduced into the polymerization reactor in one step using the modifier.

The following compounds are particularly suitable as conjugated dienes: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene (pipylene), 2,3-dimethyl 1,3-butadiene and 1,3-hexadiene. 1,3-Butadiene and isoprene are particularly preferred.

For the copolymerization with the conjugated dienes such. For example, the following 10 vinyl aromatic compounds are considered: 3-methylstyrene, 4-methylstyrene, styrene, 1-vinylnaphthalene and 2-vinylnaphthalene, styrene being particularly preferred. Both the vinyl aromatic compounds and the conjugated dienes can be used individually or as a mixture with one another. 15 A variant of the process according to the invention consists in coupling the polymerization units obtained after the monomers have been largely reacted with a coupling agent to form star-shaped polymers. Suitable coupling agents for this purpose are, in particular, tetrahalides of the elements silicon, germanium, tin and lead as well as aromatics which carry at least 2 vinyl groups, such as, for. B. 1,3,5-trivinylbenzene and 1,3- and 1,4-divinylbenzene.

^ The polymerization is generally carried out in the temperature range from 50 to 90 25 ° C. The polymerization is preferably carried out at temperatures from 80 to 150.degree. Coupling is carried out in particular at temperatures from 0 to 150 ° C., preferably 40 to 100 ° C. The process can be operated batchwise or continuously.

If the amorphous polymers obtained are to be processed into vulcanizates, they are mixed in particular with active, reinforcing fillers, a vulcanizing agent and customary additives. The active and inactive fillers used in the rubber industry are used as fillers. Primarily, these are the highly disperse silicas treated with silane coupling agents with specific surface areas of 5 to 1,000 m ² / g, preferably 20 to 400 m ² / g, and with primary particle sizes from 10 to 400 nm and carbon blacks with BET surfaces of 20-200 m ² / g. The fillers can be used alone or as a mixture of different fillers.

Masses which are intended for the production of tire treads are generally formed into raw tread strips. In the case of homogenization and shaping, which can be carried out, for example, in an extruder, the conditions of temperature and time are chosen so that no vulcanization occurs.

The rubber component consists in this case, for example, 10 to 70% by mass of a reaction product obtainable according to the invention and 90 to 30% by mass of a known, amorphous, highly unsaturated general-purpose rubber, such as. B. styrene / butadiene rubber, 1, 4-cis polybutadiene, 1, 4-cis polyisoprene and natural rubber.

Usual vulcanizing agents contain e.g. B. sulfur in combination with accelerator. The amount of the vulcanizing agent depends on the other components in the vulcanizable mass and can be determined by simple, orientation tests.

As an additive, the usual plasticizing oils in rubber technology, preferably aromatic, aliphatic and naphthenic and paraffinic hydrocarbons, as well as conventional auxiliaries such as zinc oxide, stearic acid, resin acids, anti-aging agents and ozone protection waxes, can be added in the usual amounts. The new, label-free naphthenic process oils of the type TDAE (Treated Distillate Aromatic Extracts), such as. B. BP Vivatec ^® 500, or of the type MES (Müdly Refined Solvates), such as. B. BP Vivatec ^® 200.

The polymers according to the invention are particularly suitable for the production of treads for car and truck tires, both for the production of new tires and for the retreading of old tires. The tire treads obtained are characterized by an excellent braking effect both when ABS braking and when braking on wet roads. Also to be emphasized is the extraordinarily high reversibility ons stability in the vulcanization process and the extraordinarily high network stability of the tire treads under dynamic stress.

Further refinements, modifications and variations of the present invention are readily recognizable and realizable for the person skilled in the art on reading the description, without thereby leaving the scope of the present invention.

The present invention is illustrated by means of the following exemplary embodiments, which, however, in no way limit the present invention.

embodiments

The alcoholates can be with standard methods such as. B. in Ullmann's Encyclopedia of Industrial Chemistry, Volume AI, page 298, 1985, produce. The alcoholates are used in the form of an approximately 30 to 50% solution in heptane.

The modifiers 1, 1, 2-triethoxyethane (TEE) and l, l-diethoxy-2-methoxyethane (DEME) are commercially available from Aldrich and Lancaster Synthesis.

The polymers according to the invention are produced as follows:

A hydrocarbon mixture which consists of approximately 50% n-hepane and is referred to as a C ₆ cut is used as the solvent. Further components of this mixture are in particular pentane, heptane and octane and their isomers. The solvent is dried over a molecular sieve with a pore size of 0.4 nm, so that the water content is reduced to below 10 ppm, and then stripped with sodium. The organic lithium compound is n-butyllithium ("n-BuLi" or "BuLi"), which is used in the form of a 15% by weight solution in hexane. Isoprene is separated from the stabilizer by distillation before use. The modifiers are dried over aluminum oxide and then titrated with n-butyllithium in the presence of o-phenanthroline. The microstructure of the polymers is determined by 1H-NMR. In order to be able to compare the speeds of the polymerizations carried out with the individual regulators, the reaction rate constant is calculated from the time / conversion curves in accordance with a first order reaction. The following examples serve to further illustrate the present invention without, however, restricting its scope. The following compounds are used as modifiers: TEE = 1,1,2-triethoxyethane DEME = l, l-diethoxy-2-methoxyethane example 1

700 g of heptane, 75 g (1.10 mol) of isoprene and 0.689 g of TEE (4.25 mmol) as modifiers are introduced into a 2-1 steel autoclave under a nitrogen atmosphere. After tempering to 70 ° C., the reactor contents are titrated with 0.4 mmol of n-butyllithium (14% solution in hexane) until the color changes, after addition of 1 ml of 1% benzene o-phenanthroline solution, and the polymerization is carried out by adding started from 0.85 mmol n-butyllithium. The polymerization temperature is kept at 70 ° C isothermally. After 30 minutes, a sample is taken and the conversion is determined. The polymerization is stopped after two hours. The 3,4-polyisoprene was stabilized with 0.5% BKF and worked up by precipitation with isopropanol / methanol and subsequent drying at 50 ° C. Example 2 700 g of heptane, 75 g (1.10 mol) of isoprene and 0.629 g of DEME (4.25 mmol) are introduced as modifiers into a 2-1 steel autoclave under a nitrogen atmosphere. After the temperature has been raised to 70 ° C., the contents of the reactor are titrated with 0.4 mmol of n-butyllithium (14% strength solution in hexane) until the color changes, after addition of 0.95 ml of 1% benzene o-phenanthroline solution, and the polymerization started by adding 0.85 mmol of n-butyllithium. The polymerization temperature is kept isothermally at 70 ° C. After 30 minutes, a sample is taken and the conversion is determined. Further processing is carried out as in Example 1.

The results of these tests are summarized in Table 1.

Table 1: Polymerization of isoprene at 70 ° C molar ratio modifier - / n-BuLi = 5/1

Claims

claims:

Process for the preparation of optionally coupled non-blocking polymers based on conjugated dienes or copolymers based on conjugated dienes and vinylaromatic compounds by anionic polymerization in an inert organic solvent in the presence of a catalyst system, characterized in that the catalyst system (a) comprises at least one organolithium compound as Initiator, (b) comprises at least one polar multidentate acetal compound as a modifier and (c) optionally at least one alcoholate.

2. The method according to claim 1, characterized in that an alcoholate of the following general formula M ¹ - OR ^* or R'OM -OR "is used as the alcoholate, where • M denotes an alkali metal, preferably lithium, potassium or sodium; • M denotes an alkaline earth metal, preferably calcium or magnesium; and R 'and R ", each independently of one another, denote an alkyl, aryl, arylalkyl radical or a hydrocarbon radical which contains oxygen and / or nitrogen. Process according to Claim 1 or 2, characterized in that the following alkyl acetals according to the general formula (I) are used as modifiers

can be used, whereby:

A denotes a radical -OR ¹ or a radical -NR ⁴ R ⁵ , where R ¹ , R ⁴ and R ⁵ , each independently of the other, denote a C _r C ₄ alkyl radical;

• B denotes a C _r C ₄ alkyl radical or a radical -OR ⁶ with R ⁶ = C _r C ₄ alkyl or is hydrogen;

• R ⁷ denotes a C, -C ₄ alkyl radical or is hydrogen;

• R and R, each independently of one another, represent C _r C - alkyl radicals or else R and R are bonded to one another and together form an alkylene group, in particular an ethylene, propylene or butylene group, by a five, six or to form a seven-membered ring (1,3-dioxolane, 1,3-dioxane or 1,3-dioxepane ring); • m is 0 or 1; and • n is 0, 1 or 2; but with the proviso that A denotes a residue -OR ¹ , as previously defined, and B denotes a residue -OR ⁶ , as previously defined, when n = 0 and m = 0.

Process according to one of Claims 1 to 3, characterized in that the following alkyl acetals according to the general formula (I a) are used as modifiers are used, wherein • A denotes a radical -OR ¹ or a radical -NR ⁴ R ⁵ , where R ¹ , R ⁴ and R ⁵ , each independently of the other, denote a C _r C alkyl radical; • B denotes a C _r C ₄ alkyl radical or a radical -OR ⁶ with R ⁶ = C _r C ₄ alkyl or is hydrogen; • R and R, each independently of one another, represent C _r C ₄ alkyl radicals; and • n is 0, 1 or 2.

5. The method according to Anspmch 4, characterized in that the radicals R to R ⁵ , each independently of the other, represent a methyl or ethyl radical, preferably an ethyl radical, the radical B denotes hydrogen and n is 0 or 1.

Process according to Claim 4 or 5, characterized in that the alkyl radicals R ¹ to R ⁵ , each independently of one another, represent a methyl or ethyl radical, the radical A denotes a group —OR ¹ , as previously defined, and the radical B denotes hydrogen and n is 0 or 1.

Process according to Claim 3 or 4, characterized in that alkyl acetals selected from the group of 1,1,2-triethoxyethane, l, l-diethoxy-2-methoxyethane, 1-ethoxy-1, 2- dimethoxyethane, 1, 1, 2-trimethoxyethane, 2-ethoxy-1, 1-dimethoxy-ethane, 1,2-diethoxy-l-methoxyethane and (2-methoxyethoxy) -acetalde-hyddimethylacetal.

8. The method according to Anspmch 3 or 4, characterized in that alkyl acetals are used as modifiers, which are selected from the group of 1,1,2,2-tetraethoxyethane, 1,1,2,2-tetramethoxyethane, 1,1, 3,3-tetraethoxypropane and 1,1,3, 3-tetramethoxypropane.

9. The method according to any one of claims 1 to 3, characterized in that the following substituted 1,3-dioxolanes according to the general formula (I b) as modifiers

are used, the radical R independently denoting a C _r C ₄ alkyl radical or hydrogen, x being 0, 1 or 2 and which in radicals R, R and R, each independently of one another, represent C _r C ₄ alkyl radicals ,

10. The method according to Anspmch 9, characterized in that the radical R represents a methyl or ethyl radical, preferably a methyl radical, the radicals R ⁹ and R ¹⁰ , each independently of the other, represent methyl or ethyl radicals, the radical R is hydrogen and x is 0.

11. The method according to Anspmch 9 or 10, characterized in that the modifier is selected from 2,2-dimethoxymethyl-1,3-dioxolane and 2,2-diethoxymethyl-1,3-dioxolane.

12. The method according to any one of claims 1 to 11, characterized in that the alcoholates are derived from alcohols which are selected from the group of the following alcohols: dimethylethanolamine, N, N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N- Butyldiethanolamine, triethanolamine, N, N-dimethylisopropanolamine, N- methyldiethanolamine, 2- (2- (dimethylamino) ethyl) methylaminoethanol, 2- (2- (dimethylamino) ethoxy) ethanol, tetrahydrofurfuryl alcohol, 2-hy- Droxymethyl-1,3-dioxolane, N- (2-hydroxyethyl) morpholine, tert-butanol, 2,2-diethoxyethanol or 2,2-dimethoxyethanol.

13. The method according to any one of claims 1 to 11, characterized in that the catalyst system comprises no alcoholate (c) and / or that the modifiers (b), as defined in claims 1 to 11, alone, without the simultaneous presence of an alcoholate ( c), are used with the organolithium initiator.

14. The method according to any one of claims 1 to 12, characterized in that the molar ratio initiator / alcoholate is in the range from 1: 0.1 to 1:10, preferably 1: 0.1 to 1: 1.

15. The method according to any one of claims 1 to 14, characterized in that the polymerization is carried out at constant temperature or increasing temperature, in particular in the temperature range from 40 ° C to 150 ° C, preferably at temperatures above 70 ° C and / or that the polymerization is carried out as a batch process or as a continuous polymerization.

16. The method according to any one of claims 1 to 12, 14 or 15, characterized in that 2,2-diethoxyethanol or 2,2-dimethoxyethanol is used as the alcoholate, in particular in which case the alcoholate (c) alone, without Modifier (b) can be used, styrene, butadiene and / or isoprene being particularly preferably used as monomers in this case.

17. The method according to any one of claims 1 to 16, characterized in that the following monomer mixtures are used, the percentages based in each case on the weight of the mixture: (i) mixture of isoprene and up to 75% by weight of butadiene (ii ) Mixture of isoprene and up to 50% by weight of styrene (iii) Mixture of butadiene and up to 50% by weight of styrene (iv) A mixture of 15 to 75% by weight of butadiene, 20 to 85% by weight of isoprene and up to 50% by weight of styrene.

18. The method according to any one of claims 1 to 17, characterized in that the modifiers, as defined in claims 1 to 1 1, can be used in any combination with one another and / or that modifiers, as defined in claims 1 to 11, dosed over the course of the polymerization, in particular with a two to three dosing being particularly preferred, and / or in that the molar ratio of modifier / initiator is in particular in the range from 0.1: 1 to 15: 1, preferably 1: 1 to 5 : 1, lies.

19. The method according to any one of claims 1 to 18, characterized in that a coupling agent is added to the polymerization batch at the end of the reaction.

20. The method according to Anspmch 19, characterized in that aromatics with several vinyl groups, alkyl aromatics with several vinyl groups, such as di- or trivinylbenzene, or silicon tetrachloride or tin tetrachloride are used as coupling agents.

21. Polymers which can be prepared by the process according to claims 1 to 20.

22. Use of the polymers obtainable by the process according to claims 1 to 20 for the production of damping materials, tires and tire components, such as tire treads or sidewalls.

23. Use of the polymers obtainable by the process according to claims 1 to 20 for the production of technical rubber articles.

24. Use of the polymers obtainable by the process according to claims 1 to 20 for modifying plastics.

25. Use of the catalyst system as defined in claims 1 to 20 for the production of (co) polymers based on conjugated dienes and optionally monovinylaromatic compounds.

26. Use of the catalyst system as defined in claims 1 to 20 for the anionic polymerization, in particular for the anionic polymerization of at least two monomers from the group of butadiene, isoprene and styrene.

27. Damping materials, tires and tire components, such as tire treads or sidewalls, as well as technical rubber articles, produced on the basis of polymers obtainable by the process according to claims 1 to 20.